Composition for rendering printing rollers nonmeltable



Patented June 3, 1952 "CUM PDSITIDN IOR RENDERING PRINTING ROLLERS NONMELTABLE Lloyd Warren Conklin, Toronto, Ontario, Canada No Drawing. Application November 9, 1948, Serial No. 59,193

This invention generally relates to a method for rendering glue-glycerin printing rollers nonmeltable, and to a grease for coating rollers in the course of rendering them non-meltable.

Printing rollers, having a glue-glycerin base, have been known for many years. Early glueglycerin printing rollers possessed the disadvantage that under the atmospheric conditions encountered during use, the rollers tended to melt, losing their truly cylindrical shape, and thereby becoming useless. This problem of melting was met as follows. Glue-glycerin printing rollers are made by a casting process somewhat analogous to the casting of metals in molds. It was found that if, when the glue-glycerin mixture was in a molten condition prior to casting, a small amount of hexamethylenetetramine was added, a printing roller resulted from the casting process which, after a suitable curing process, was non-meltable under the atmospheric conditions such rollers are normally called upon to face.

However, the solution of the melting problem introduced a new problem. The roller casting process must be followed by a cleaning up or trimming of the resulting roller. Excess roller material in the form of heads, tails, plates and the like, bad to be removed. The material removed in the trimming operation represented a substantial percentage of the glue-glycerin (plus hexamethylenetetramine) mixture used in manufacturing the roller. Now these trimmings were in a non-meltable form and, therefore, could not be directly turned back into the process of making new rollers. The industry was faced with the disposal of by-products which bore little value. This virtually waste material was sometimes sold to adhesive manufacturers (who recovered the glycerin), or was finely chopped up, and added in small percentages to large bodies of virgin glue-glycerin material being prepared for roller making. Often no outlet was found for the material.

It is therefore the prime object of this invention to provide a method for making non-meltable glue-glycerin rollers which leaves the trimmings from the casting process in such condition that they may be melted and directly returned to roller manufacturing process.

It is a further object of the invention to provide a coating which may be applied to a cast and trimmed glue-glycerin roller to render the roller non-meltable after a suitable curing eriod.

With these and other objects in view my in- 1 Claim. (Cl. 106-243) vention generally consists in a method of manufacturing non-meltable glue-glycerin rollers, comprising the steps of heating a mixture of glue, glycerin and water unti1 the mixture is molten, forming a roller about a core by casting the molten mixture in a mold wherein the core is centered, removing the cast roller, trimming excess glue-glycerin material from the cast roller, coating the trimmed roller with a grease containing hexamethylene-tetramine and curing the coated roller under controlled conditions of temperature and humidity.

In order to practice my invention, it was necessary to develop a suitable vehicle for carrying the hexamethylenetetramine which would enable the hexamethylenetetramine to be coated on the roller in a facile manner. I have found that the hexamethylenetetramine is best applied to the roller by coating it thereon in a grease form. One grease which I have found to be eminently suitable is made up of lanolin 6 parts, glycerin 2 parts, and hexamethylenetetramine 1 part. This mixture is heated to about 260 F. and allowed to cool. When cooled to about 80 F. it is in the form of a grease which may be spread over the trimmed roller in a simple manner. Whilst lanolin and glycerin are the best components which I have so far found for making this grease, substitutes may be made for both the lanolin and the glycerin depending upon cost and availability factors.

As a substitute for lanolin, I have found that any grease with a melting point below substantially F. is suitable, and as a substitute for glycerin, an alcohol with a boiling point in excess of substantially 250 F. may be used.

I recommend that the grease be stirred shortly before application thereof in order to counter-act any separation which may have occurred.

Rollers coated with this grease are then cured by storing under. controlled conditions of temperature and humidity. I prefer to store the rollers for some thirty days at a temperature of 90 F. and a relative humidity of 55%. During this storage of the rollers, the hexamethylenetetramine penetrates the glue-glycerin material and forms a non-meltable shell.

The applicant fully realises that the treating of a glue-glycerin printing roller with hexamethylenetetramine is not new and that the curing stage mentioned is not new. The invention resides only in the order in which the various steps of the method are carried out and in the grease composition itself which is employed in carrying out the new method.

What I claim as my invention is: A composition for coating glue-glycerin printing rollers during the course of rendering them non-meltable, consisting of hexamethylenetetramine, lanolin, and glycerin, substantially in proportions of one part, six parts and two parts, respectively.

LLOYD WARREN CONKLIN.

REFERENCES CITED The following references are of record in the; V

file of this patent;

4 UNITED STATES PATENTS Number Number 0 9 m 12,677 of 1914 2,167 of 1915 Name Date Crump Mar. 8, 1904 Sohn Feb. 13, 1917 Adams Sept. 30, 1919 FOREIGN PATENTS Country Date Great Britain Feb. 20, 1911 Great Britain Dec. 24, 1914 Great Britain Feb. 10, 1916 

